Scientists at Northwestern University have developed a highly efficient, environmentally friendly method for converting ammonia to hydrogen. The study, published in the journal Joule, is an important step towards a zero-emission, hydrogen-fueled economy.
The idea of using ammonia as a carrier for hydrogen delivery has gained popularity in recent years. The fact is that this binary inorganic chemical compound is much easier to liquefy than hydrogen. This means that it is easier to store and transport.
To convert ammonia, scientists built a unique electrochemical cell with a proton-conducting membrane and integrated it with a decomposition catalyst.
First, ammonia “meets” the catalyst, which splits it into nitrogen and hydrogen. The resulting hydrogen is immediately converted into protons, which are then electrically transported across the membrane in the electrochemical cell. By constantly taking hydrogen away, scientists are pushing the reaction further and further. This type of reaction is known as the Le Chatelier-Brown principle. By removing one of the products of ammonia breakdown – namely hydrogen – the process is moving beyond what a conventional catalyst can do.
The resulting hydrogen can be used in a fuel cell. Like batteries, fuel cells generate electricity by converting energy from chemical reactions. Unlike batteries, they generate electricity as long as there is fuel and never lose their charge. Hydrogen is a clean fuel that, when consumed, produces water as its only by-product. These properties distinguish it from a fossil, whose byproducts – carbon dioxide, methane and nitrous oxide – change the climate and heat the planet.
The new method is distinguished by its environmental friendliness. Renewable electricity is used to convert ammonia to hydrogen instead of fossil fuel heat. The entire process takes place at lower temperatures than traditional splitting methods (250 ° C instead of 500-600 ° C). In addition, the new technology generates pure hydrogen that does not need to be separated from unreacted ammonia or other products. The process is also efficient – all the electric current supplied to the device directly produces hydrogen without any losses for parasitic reactions.
The study’s authors predict that new technology could dramatically change the transport sector. In 2018, the movement of people and goods by cars, trucks, trains, ships, airplanes, and other vehicles accounted for 28% of North America’s greenhouse gas emissions, according to the U.S. EPA – more than any other sector. economy.